Introduction: Team chopsticks, Ziqiu Li, Charles Shearer, Andrew Spahr
Technology Selected: The cell phone
Our team chose cell phone technology due to its increasing role in our society. We all use cell
phones but we don’t really understand how they work. Our goal is to shed some light on how
the cell phone works and technology uses. We will take it from infancy to its current’s
technology state. We will explain the components of the phone, the equipment, the phone
talks to and the medium it uses. We chose this technology due to the fact that is it has such a
wide use in our society. It has evolved from a large bulky mobile car phone to a complex
multimedia device that can be as small as a credit card. It has the ability to send and receive
voice, data, pictures, text, video and many other forms of multimedia. To start off, cell phone is
basically a radio. We going to explain what is a cell phone, how it works, and who uses it. Cell
phone technology is advancing in a rapid pace, we all uses it in business, socializing, and for
multi-media, and for downloading data. Companies like Verizon, sprint, T-mobile, sony, and
many more have built the infrastructure in phones, completing international switching stations
in cellular grids enabling us to communicate uninterrupted. The technology used is part
computer chip, circuit board, radio frequency, digital cellular tower, switching stations, and
human interaction. It is gone from 1G to 3G in terms of stages. Currently, we are entering the
3G, third generation, of technology of expanding our communication abilities. Let’s take a look
at how the cell phone has evolved.
The concept of the cell phone began in 1947. They were originally intended to be mobile car
phones that could reuse frequencies traveling before small cell ranges. They were actually
radio telephones. These early mobile phones were actually introduced to automobiles first, and
were half duplex in nature, thus meaning they can only carry one way communication at a time.
For example, policeman utilizing the radio could send his message and would have to wait for
the reply to be return to him on another frequency. At that time, there was only one tower per
city with only about 25 channels available on that tower. That meant that the phone in your car
had to have a powerful transmitter that could reach 40 to 50 miles. Obviously not too many
people could use the radio telephones; there were not enough channels. In 1968, the Federal
Communication Commission (FCC) reconsidered its position in increased the elocution of
frequencies. Dr. Martin Cooper, a manager from Motorola considered being the inventor of
first portable handset and he made first call on the phone on 1973. At that time, bell
laboratories introduced cell technology in police cars. However, Motorola was the first
company to design cell phone for use outside of automobile. In the late 70s, Bell labs
constructed first proto types of cellular systems. Tokyo, Japan soon followed. That brings to us
today.
This is a cell phone circuit board
containing the digital analog processor, the digital signal processor, the ROM, flash memory and the RF amplifiers.
To explain a little bit of the background and history of the cell phone; we will introduce you to
one of pioneers of the technology. Dr Martin Cooper, a former general manager for the systems
division at Motorola, is considered the inventor of the first modern portable handset. Cooper
made the first call on a portable cell phone in April 1973. He made the call to his rival, Joel
Engel, Bell Labs head of research. Bell Laboratories introduced the idea of cellular
communications in 1947 with the police car technology. However, Motorola was the first to
incorporate the technology into portable device that was designed for outside of an automobile
use. Cooper and his co-inventors are listed above. By 1977, AT&T and Bell Labs had constructed
a prototype cellular system. A year later, public trials of the new system were started in Chicago
with over 2000 trial customers. In 1979, in a separate venture, the first commercial cellular
telephone system began operation in Tokyo. In 1981, Motorola and American Radio telephone
started a second U.S. cellular radio-telephone system test in the Washington/Baltimore area.
By 1982, the slow-moving FCC finally authorized commercial cellular service for the USA. A year
later, the first American commercial analog cellular service or AMPS (Advanced Mobile Phone
Service) was made available in Chicago by Ameritech.
Despite the incredible demand, it took cellular phone service 37 years to become commercially
available in the United States. Consumer demand quickly outstripped the 1982
Dr. Martin Cooper
Let’s compare a cell phone with other forms of radio communication. Take the walkie talkie
and the CB radio as examples. They use what is referred to as half duplex technology. Where
two people use the same frequency allowing only one person to talk at a time. The walkie
talkie uses one channel. The CB radio uses 40 channels. A cell phone can use up to 1664
channels or more. The walkie talkie can transmit approximately one mile and the CB radio
about five miles. The cell phone can cross multiple cellular grids and continue to hold its signal.
Today cell phones utilize full duplex technology (2G, 3G) and cellular grids carrying multiple
frequencies allowing multiple users to carry multiple conversations at any moment. With the
advancement of the digital technology, these frequencies are broken down into even more
channels allowing compression of the signal, and greater switching frequency. 3G technologies
basically is the utilization and expansion of the digital technology comprising multimedia, data
voice, video, games, television, internet, message, music, and any other PED (personal digital
assistance).
Quite simply put the cell phone is a radio utilizing its frequencies to carry voice, data, and
relaying data between cellular areas. The genius of the cell phone is that the cities are broken
up into small cells. This allows extensive reuse of the frequencies across the city. This led to
first generation (1G) terminology to classify the initial analog cell phones. This analog
technology used the 800 MHz frequency range in each city. Now to better understand cells,
consider a city broken into 10 mile areas, these areas are the boundary of the cells, and within
these cells service and carrier acquire multiple frequencies to broadcast. Within these cells
there is a base station (picture) and radio equipment; T1.
As a note, the following information is recently published
regarding analog cell phone service. If you're one of those slow
adopters who like to keep your old cellular phone around, it's finally time
to ditch it for a newer model.
Analog cell phones will no longer work after midnight Feb. 18, according to
the Cedar Rapids police and fire departments.
That means you can't count on them any more to make 911 calls.
Cellular companies, which long ago transitioned most of their customers to
digital handsets, are allowed by the Federal Communications to deactivate
their networks on that date, according to Verizon Wireless spokeswoman Karen
Smith.
Deactivating the analog networks is preferable to most cellular providers,
because so few customers use them, and they involve considerable cost to
operate and maintain.
Smith said Verizon, after repeatedly encouraging customers to come in for new
digital handsets, mailed out free digital handsets to the last remaining
holdouts last month with instructions to go to a Verizon store to have them
activated.
"We've been proactively calling all of them for a year," Smith said. "It's
less than one half of one percent that still have the old analog phones." If
a customer is unsure whether their old phone is analog, Smith said the lack
of advanced functions available in digital handsets is the best tip-off that
it really is an oldster.
Analog handsets don't have text messaging, integrated cameras or other
goodies such as integrated MP3 players.
Cellular phone users who are unsure if their phone is analog should take it
to their service provider's nearest store for a determination.
A handful of cellular providers have said they'll keep providing analog
service past the FCC sunset date, but most plan to discontinue analog service
this year.
Let’s look at how the carrier communicates with our phones. Carrier utilizes the frequencies
within the cell by central switching office. The central switching office is a landline base station
controlled by the carrier. All the towers, cellular carriers owns our managed through the central
switching office. Now, the carrier utilizes frequencies within the cellular areas to communicate,
control, the data and voice with the phone call. The central switching office maintains a data
base containing all the base stations at the towers, who in turn contain all of the frequencies.
Now when the central switching office needs to contact a particular cellular grid during the flow
of a phone call, it contacts a base station which contacts the cellular phone via the control chip,
and the control frequency within the cell. This base station identifies the phone via System
Identification Code (SID) in your phone. The SID is a unique five digit number that’s assigned to
each carrier by the Federal Communication Commission (FCC). This SID coupled with electronic
serial number (ESN), which is a unique number that is programmed in your phone when it’s
manufactured. For example, we powered the phone; it listens for the SID on the control
channel, which is broadcast on the control frequency from the base station. What happens here
is the base station and your phone now communicate channel changing, frequency to be used,
and any other unique identifiers. Now your phone will receive the SID, and compare to the ones
that has inside, if the SIDs match, then it knows it is talking to its home carrier. Now here is the
interesting part. Once the SID has identified to the home network, it will now transmit to the
Mobile Telephone Switching Office (MTSO). The MTSO keeps track of your phone’s location and
its data base. This is how your MTSO knows which cell you are in, and can ring your phone. Now
in the mean time, the MTSO has turned on the frequency in the tower in your cellular area and
locked it to your phone and your call is connected. As you travel and move, remember cellular
grids are about 10 miles radius from tower to tower, at this time, your MTSO is constantly
tracking you, knowing when to switch to another tower.
Here is the wiring at a base station; you can see the grounding plate.
This box houses the radio transmitters and
receivers that communicate with the phones
There are also multi mode cell phones meaning dual band and dual mode cell phone
technology. These refer to cell phones that have multiple band capability. The multi band type
of cell phone can utilize frequencies between 800 MHz all the way through 1900 MHz range.
The multi mode cell phone can use different transmission types. They use AMPS or TDMA
transmission types and switch between them if needed. These cell phones are generally good
when travelling in different areas of the world. In Europe and Asia they use the 900 MHz
frequency and in the U.S. we use the 1900 MHz range. These cell phones can switch
automatically when needed.
With all of these switching power used in digital technology (2G, 3G), these phones require a lot
of processing power. Let’s take a look at the guts of the digital cell phone. They are some of the
most intricate devices we use. They process millions of calculations per second to compress,
decompress switch the voice, data, moves, music, and all the other multimedia tasks we require
doing. There really are only a few parts which makes its design more impressive. The parts to
make up the phone are:
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Circuit board containing the brains of the phone
Antenna
LCD
Keypad
Microphone
Speaker
Battery
The circuit board is the most important due to contain the chips. There is the digital to analog,
analog to digital processor. This obviously compresses the data then decompresses it so it can
be heard in analog format. The digital signal processor (DSP) is a highly customizable processor
that performs calculations. The micro-processor holds all the housekeeping chores. It
communicates with the base station. The ROM and flash chips store the phones operating
systems. Radio frequency and antenna. As you see, it is very complex device.
Some popular cell phone models with multimedia capability
We as a group have learned great deal about how our cell phones that we rely on really work.
We have learned that they are actually radios processing digitized, compressed, video, images,
voice, data and satellite signals. We now understand as we travel how our cell phone
communicates across multiple cellular grids and constant contact with the MTSO. We have
attempted to explain what it is, how it works, and obviously we all use it. We feel this
technology is only going to explode in the future. We know we will be able to use our phones
for everything from buying food, gas to contain our accounts, personal IDs.
The script for our video presentation included the introductory and conclusion cell phone conversations.
They included an outside participant along with Ziqui Li and Charles Shearer. The video was captured
over multiple days encompassing areas on campus, in some labs and in the dormitory area. We met at
various times and coordinated via cell phone and email.
Responsibilities Included:
Charles Shearer: Research and Narration
Ziqui Li: Filming; Video editing
Andrew Sphar: Statistics and planning
Problems overcame; Work and class schedules; Charles works full time and has a part time job some
nights; Ziqui works at night also and Andrew had class some nights so we had to arrange different times
that we could all get there or submit our portions to the members that could get together to put it
together.
Statistics and reference: were gathered through various websites including but not limited to
www.howstuffworks.com and FCC statistics.